Calcium roles

1. CALCIUM
Devraj Singh
Deeksha yadav

2. Content
• Introduction to calcium
• Sources
• Dietary requirement
• Calcium absorption
• Biochemical function
• Calcium in blood
• Disease states

3. Introduction
• Most abundant among minerals in the body.
• Total content in adult man=about 1-1.5kg.
• 99% of calcium is present in bone and teeth.
• 1% calcium found outside the skeletal muscles,
perform a wide variety of function.

5. Dietary requirements
• Adult men and women = 800mg/day
• During pregnancy,lactation and post-menopause=
1.5gm/day
• Children(1-18yrs)= 0.8-1.2g/day
• Infants(<1yrs)= 300-500mg/day

6. Calcium absorption
• Calcium absorption mainly occurs in duodenum by an
energy dependent active process.
• Factors promoting calcium absorption:
1. Vitamin D ( through its active form calcitriol) induce
the synthesis of calcium binding protein in the
intestinal epithelial cells and promote calcium
absorption.

7. 2. Parathyroid hormone enhance calcium transport from
the intestinal cells.
3. Acidity is more favourable for calcium absorption.
4. Lactose promote calcium uptake by intestinal cells.
5. The amino acid lysine and arginine faciliate calcium
absorption.

8. Factors inhibiting calcium absorption:
1. Phytates and oxalate form insoluble salts that
interfere ca absorption.
2. High content of dietary phosphate forms insoluble
calcium phosphate and prevents ca uptake.
4. The dietary ratio of ca and p -1:2 and 2:1 is ideal for
optimum calcium absorption by intestinal cells.
5. Alkaline condition is unfavourable for ca absorption.

9. Biochemical function
1. Development of bone and teeth
2. Nerve transmission
3. Muscle contraction and relaxation
4. Calcium calmodulin complex
5. Secretion of Hormones
6. Membrane integrity and permeability
7. Blood coagulation
8. Ca as intracellular Messenger

10. Blood level of calcium
• Normal calcium level in blood is 9-11mg/dl.
• Three physiochemical states:
✓free/ ionised- 50%
✓Protein bound- 45%
✓Complexed - 5%

11. - Free form is the biologically active form.
- Proteins-mostly with albumins and to some extent,
with globulins.
- Complexed – with small diffusible organic and
inorganic anions eg. HCO3-, H2PO4-, citrate, lactate.

12. Diseases states
1. Hypercalcemia:
➢ Elevated serum ca level (>11mg/dl)
➢ Associated with hyper parathyroidism, caused by
increased activity of parathyroid gland.
➢ There is osteoporosis and X-ray shows punched out
areas of bone resorption.(osteitis fibrosa cystica
generalictica or von Recklinghaysen’s diseases).

13. ➢ Pathological fracture of bone may result.
➢ In urine, ca is excreted, which may cause inhibition
of elimination of chloride and that may lead to
hypercholerimic acidosis.
➢ Ca may be precipitated in urine,leading to recurrent
bilateral urinary calculi.

14. ➢Ectopic calcification may be seen in renal tissue,
pancreas, arterial walls and muscle tissues.
➢Symptoms of hypercalcemia include:
• Lethargy, muscle weakness, loss of appetite,
constipation, nausea, increased myocardial
contractility and suseptibility to fracture.

15. ❑Other minor causes of hypercalcemia;
▪ In multiple myeloma, paget’s diseases and metastatic
carcinoma of bone, there will be bone resorption and
mild hypercalcemia.
▪ Increased absorption of ca from intestine is seen in
milk-alkali syndrome and vit.D toxicity.
▪ Lithium therapy and thiazide diuretics may also causes
mild hypercalcemia.

16. 2. Hypocalcemia:
➢ Condition where ca level is < 8.8 mg/dl.
➢ If,ca level < 8.5 mg/dl, there will be mild tremors.
➢ If ,ca level <7.5 mg/dl, tetany a life threatening
condition result.

17. ➢ Tetany may be due to accidental surgical removal of
parathyroid glands or by autoimmune diseases.
➢ Main manifestation are carpopedal spasm ;
laryngismus and stridulus.
➢ Laryngeal spasm may lead to death.

18. ➢Clinical signs are chovstek’s sign(tapping over 5th
cranial nerve causes facial contraction) and Trousseu’s
sign(inflation of B.P cuff causes carpopedal spasm.)
➢Increased Q-T interval in ECG.
➢Urinary excretion of both ca and P is decreased.
➢Treatment: Give intravenous injection of ca salts.

19. 3. Rickets:
➢ Disorder of defective calcification of bone.
➢ Due to low level of vit.D in body or due to dietary
deficiency of ca and P –or both.
➢ Characteristic feature of rickets-increased activity of
alkaline phosphatase activity.

21. 4. osteoporosis: Charecterized by demineralisation
of bone resulting in the progressive loss of bone
mass.
❑ Occurrence: Elderly people(over 60 yrs) of both
sexes are at risk; however >post menopausal
women.
➢ Osteoporosis result in frequent bone fracture
which is the main cause of disability in elderly
people.

22. ❑ Etiology:
➢ Believed that several causative factors may contribute to it.
➢ The ability to produce calcitriol from vit.D is reduced with
age, particularly in postmenopausal women

23. ➢Immobilized or sedentary individual tend to decrease
bone mass while those on regular exercise tend to
increase bone mass.
➢Deficiency of sex hormones (in women) has been
implicated in the development of osteoporosis.

24. ❑Treatment:
➢Estrogen supplementation along with ca (in
combination with vit.D) to postmenopausal women
reduces risk of fracture.
➢Higher dietary intake of ca (abt.1.5 g/day) is
recommended for elderly people.

25. 5. Osteopetrosis(marble bone diseases):
➢ Charecterized by increased bone density.
➢ Mainly due to inability to resorb bone.
➢ Disorder mainly associated with renal tubular
acidosis(due to defect in the enzyme carbonic
anhydrase) and cerebral calcification.

28. Thank you